New research suggests that occasional marijuana use among teens does not limit their long-term brain power.
British researchers found that using marijuana moderately does not appear to affect teens' intelligence or school performance. However, heavy marijuana users -- teens who have smoked marijuana at least 50 times by age 15 -- tend to have slightly lower exam scores, HealthDay reported.
"Our findings suggest cannabis may not have a detrimental effect on cognition, once we account for other related factors -- particularly cigarette and alcohol use," Claire Mokrysz, lead researcher of the study, told HealthDay. "This may suggest that previous research findings showing poorer cognitive performance in cannabis users may have resulted from the lifestyle, behavior and personal history typically associated with cannabis use, rather than cannabis use itself."
For the study, researchers collected and analyzed data from more than 2,200 U.K. children age 8 and at age 15.
They found a strong link between marijuana use and other risky behaviors such as alcohol, cigarette and drug use. Researchers said that when these other behaviors were taken into account, there was no connection between marijuana use and lower IQ at age 15.
"It's hard to know what causes what -- do kids do badly at school because they are smoking weed, or do they smoke weed because they're doing badly? This study suggests it is not as simple as saying cannabis is the problem," Mokrysz explained.
She added that the findings are a "potentially important public health message -- the belief that cannabis is particularly harmful may detract focus from and awareness of other potentially harmful behaviors."
However, she said the study results warrant further investigation.
The findings were presented this week at a meeting of the European College of Neuropsychopharmacology in Berlin, Germany.
